Picture of person typing on laptop with programming code visible on the laptop screen

World class computing and information science research at Strathclyde...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including by researchers from the Department of Computer & Information Sciences involved in mathematically structured programming, similarity and metric search, computer security, software systems, combinatronics and digital health.

The Department also includes the iSchool Research Group, which performs leading research into socio-technical phenomena and topics such as information retrieval and information seeking behaviour.


Extension of earth orbits using low-thrust propulsion

Anderson, Pamela and Macdonald, M. (2010) Extension of earth orbits using low-thrust propulsion. In: 61st International Astronautical Congress, IAC 2010, 2010-09-27 - 2010-10-01.

PDF (strathprints027416.pdf)

Download (443kB) | Preview


The primary motivation for the utilization of space for environmental science, and in-particular Earth Observation, is the unique vantage point which a spacecraft can provide. For example, a spacecraft can provide a global dataset with a much higher temporal resolution than any other platform. Earth Observation spacecraft are increasingly focused on a single primary application, typically conducted from a small set of classical orbits which limits the range of vantage points and hence the type of observations which can be made. The next generation of innovative Earth Observation spacecraft may however only be enabled through new orbit options not considered in the past. The objective of the study was therefore to enlarge the set of potential Earth orbits by considering the use of low-thrust propulsion to extend the conventional Molniya orbit. These new orbits will use existing, or near-term low-thrust propulsion technology to enable new Earth Observation science and offer a radically new set of tools for mission design. Continuous low-thrust propulsion was applied in the radial, transverse and normal directions to vary the critical inclination of the Molniya orbit, while maintaining the zero change in argument of perigee condition. As such the inclination can be freely altered from the expected critical inclination of 63.4 deg, to, for example 90 deg, creating a Polar-Molniya orbit. Analytical expressions were developed which were then validated using a numerical model, to show that not only was the argument of perigee unchanged but all other orbital elements were also unaffected by the applied low-thrust. It was shown that thrusting in the transverse direction allowed the spacecraft to achieve any inclination with the lowest thrust magnitude in any single direction; this value was however found to be further reduced by combining both radial and transverse thrust. Real-time continuous observation of the Arctic Circle is then enabled using current electric propulsion technology, with fewer spacecraft than the traditional Sun-synchronous polar orbit, and at reduced range than a 'pole-sitter'. Applications of such an orbit would include more accurate Arctic weather predictions and severe weather event warnings for this region.